JUKI MF-7700 Series Engineer's Manual

ENGINEER’S MANUAL

13371604

No.E361-01

High-speed, Flat-bed Coverstitch Machine

MF-7700 Series

PREFACE

This Engineer’s Manual is written for the technical personnel who are responsible for the service and maintenance of the machine. The Instruction Manual for these machines intended for the maintenance personnel and operators at an apparel factory contains operating instructions in detail. And this manual describes “Standard Adjustment”, “Adjustment Procedures”, “Results of Improper Adjustment”, and other important information which are not covered by the Instruction Manual. It is advisable to use the relevant Instruction Manual and Parts List together with this Engineer’s Manual when carrying out the maintenance of these machines. In addition, for the motor for the sewing machine with thread trimmer, refer to the separate Instruction Manual or Engineer’s Manual for the motor. And for the control panel, refer to the Instruction Manual for the control panel. This manual gives the “Standard Adjustment” on the former page under which the most basic adjustment value is described, and on the latter page “Results of Improper Adjustment” under which stitching errors and troubles arising from mechanical failures are described together with the “Adjustment Procedures”.

CONTENTS

1. SPECIFICATIONS ............................................................................................. 1

2. CONFIGURATION OF THE MACHINE COMPONENTS .................................. 2

3. MODEL NUMBERING SYSTEM ....................................................................... 3

4. MOTOR PULLEY AND BELT MF-7700 Series ................................................ 4

5. STANDARD ADJUSTMENT ............................................................................. 5

(1) Threading the machine head ........................................................................................... 5

(2) Adjusting the rocking thread take-up............................................................................. 7

(3) Adjusting the position of the needle thread guide rod ................................................. 9

(4) Adjusting the position of the thread receiver .............................................................. 11

(5) Adjusting the position of the spreader thread guide and spreader thread take-up ...... 13

(6) Adjusting the spreader .................................................................................................. 15

(7) Adjusting the timing relation between the looper and needle bar............................. 19

(8) Retuming amount of the looper .................................................................................... 21

(9) Height of the needle ....................................................................................................... 23

(10) Locus and longitudinal motion of the looper ............................................................ 25

(11) Adjusting the needle guard ......................................................................................... 27

(12) Instlling cover of the looper and needle guard after adjusting................................ 31

(13) Adjusting the feed dog................................................................................................. 33

(14) Adjusting the feed relation .......................................................................................... 39

(15) Adjusting the presser foot........................................................................................... 41

(16) Adjusting the micro-lifter............................................................................................. 43

(17) Adjusting the looper thread cam ................................................................................ 45

(18) How to change needle bar stroke ............................................................................... 47

(19) How to change the spreader ....................................................................................... 51

(20) With reagard to lubrication .......................................................................................... 53

(21) Adjusting and setting SC-380...................................................................................... 55

6. TROUBLES AND CORRECTIVE MEASURES............................................... 57

7. DRAWING OF TABLE (SEMI-SUBMERGED TYPE) ..................................... 71

–1 –

No. Item Specifications 1 Model name High-speed, flat-bed coverstitch machine 2 Model MF-7700 series 3 Stitch type ISO standard 406, 407, 602, and 605

4 Example of application Hemming and covering for knits and general knitted fabrics 5 Max. sewing speed Max. 6,500 rpm (at the time of intermittent operation) 6 Needle gauge 3-needle ... 4.8 mm, 5.6 mm, and 6.4 mm

2-needle ... 4.0 mm (3.2 mm can be accepted as special order)

7 Differential feed ratio 1 : 0.7 to 1 : 2 (stitch length : less than 2.5 mm)

Micro-differential feed adjustment mechanism is provided. (Micro-adjustment)

8 Stitch length 1.2 mm to 3.6 mm (can be adjusted up to 4.4 mm)

9 Needle UY128GAS ORGAN #9S to #14S (standard #10S)

(SCHMETZ Nm65 to Nm90, standard Nm70) 10 Needle bar stroke 31mm (standard), possible up to 33 mm by adjustment) 11 Dimensions (Height) 451 x (Width) 515 x (Length) 265 12 Weight 46kg 13 Lift of presser foot 8 mm (needle gauge : 5.6 mm without top covering), and 5 mm (with top covering)

Micro-lifter mechanism is provided. 14 Feed adjustment method Main feed ... dial type stitch pitch adjustment method

Differential feed ... lever adjustment method (micro-adjustment mechanism is provided.) 15 Looper mechanism Spherical rod drive method 16 Lubricating system Forced lubrication method by gear pump 17 Lubricating oil JUKI MACHINE OIL 18 (Equivalent to ISO VG18) 18 Oil reservoir capacity Oil gauge lower line : 600 cc to upper line : 900 cc 19 Installation Semi-submerged type 20 Needle tip, needle thread and Provided as standard

silicon oil lubricating unit

21 Noise Workplace-related noise at sewing speed

n= 5000 min-1 : LPA ≦78 dB (A)

Noise measurement according to DIN 45635-48-A-1.

1. SPECIFICATIONS

–2 –

2.CONFIGURATION OF THE MACHINE COMPONENTS

1 Presser spring regulator !0 Thread tension nut !9 Thread trimming knife 2 Needle bar thread take-up cover !1 Oil gauge @0 Rocking thread take-up receiver 3 Oil circulation identification window !2 Feed regulating knob @1 Rocking thread take-up 4 Oil hole cap !3 Eye guard cover @2 Front cover 5 Micro-lifter !4 Throat plate @3 Slide cover 6 "Oil" indication !5 Needle tip silicon oil lubricating unit @4 Needle bar thread take-up thread 7 Needle thread silicon !6 Differential lock nut receiver

oil lubricating unit !7 Micro-adjustment knob @5

Rocking thread take-up thread guide

8 Thread guide No. 1 !8 Finger guard @6 Silicon container thread guide 9 Upper pulley @7 Belt cover

–3 –

3.MODEL NUMBERING SYSTEM

High-Speed, Flat-bed Coverstitch Machine Applicable model : MF-7700 Series

3~6 Model code 7722 2-needle top & bottom covering stitch 7723 3-needle top & bottom covering stitch

Application code 7~9 Application Description U10 For universal Lapseam, Covering, Hemming C10 For collarette Collarette

10 Tongue shape of throat plate B B-type (Standard)

Availabilty

11~12 Needle gauge For 2-needle For 3-needle U10 C10

40 4.0mm Avail – – Avail 48 4.8mm Avail Avail Avail – 56 5.6mm Avail Avail Avail Avail 64 6.4mm Avail Avail Avail Avail

14~22 Device and attachment (blank) Not provided

24 Destination

A Standard

25 Accessory

A Standard

* When device or attachment is one, delete slash (/) of 13th digit.

1 2 3 4 5 6 7 8 9 10111213141516171819202122232425

MF 7 7 B / / –

–4 –

50Hz 60Hz

Pulley size (mm) Belt size (inch) Pulley size (mm) Belt size (inch) 4,500 ø 100 M-35 ø 85 M-35 4,800 ø 105 M-36 ø 90 M-35 5,000 ø 115 M-36 ø 95 M-35 5,500 ø 125 M-37 ø 105 M-36 5,800 ø 130 M-37 ø 110 M-36 6,000 ø 135 M-37 ø 115 M-37 6,200 ø 140 M-38 ø 120 M-38 6,500 ø 150 M-39 ø 125 M-38

4. MOTOR PULLEY AND BELT MF-7700 Series

1 . The table shows the numbers when a 3-phase 2-pole 400 W clutch motor (1 / 2 HP) is used. 2 . The commercially-available motor pulley near to the counted value is designated since the outside diameter of the

commercially-available motor pulley counts by 5 mm.

3 . When you use a new sewing machine, use the machine at a speed of 5,000 rpm or less for the first 200 hours

(approximately one month). A good result can be obtained in terms of the durability.

(Caution) 1. Use a motor pulley which is adaptable to this sewing machine.

2. The sewing speed exceeds the max. sewing speed of this sewing machine and machine trouble will be caused unless a motor pulley which is adaptable to this sewing machine is used.

Sewing speed(rpm)

–5 –

5. STANDARD ADJUSTMENT

1. Threading for standard seame

(Caution) In case of threading for standard seams, rocking thread take-up thread guide 5 is not used.

(Caution) In case of the soft seams, rocking thread take-up thread guide 5 is used.

When covering thread is excessively tense = D

When covering thread is excessively loosened = B When covering thread is excessively loosened even after passing B = C

Broken lines A when stretcher thread is used

Standard Adjustment

(1) Threading the machine head

2. Threading for soft seams (1) Do not pass needle thread through needle bar thread take-up 8. (2) When soft seams are required, change the threading of needle thread and slide the position of looper thread cam

eyelet.

(3) Do not pass needle thread through needle bar thread take-up 8. Pass the thread from rocking thread take-up 9 to

rocking thread take-up thread guide

(4) Other points are same as those of “1. Threading for standard seame”.

In case of soft seams

Engraved marker line

Left

Right

When using more stretchable thread

When using less stretchable thread

–6 –

1. When motion of thread is very rough, and stable seams can not be obtained, there are cases where the condition can be improved by the following threading. (1) Wind thread around 1st thread guide 6.

(2) Wind thread around the thread tension thread guide !0.

2. When using more stretchable thread (wooly thread or the like), the threading as given below does not make thread stretch and neat seams can be obtained. (1) Do not pass thread through spreader auxiliary thread tension 4.

(2) Do not pass thread through the looper thread tension disk.

Refer to section E.

(Caution) Even when using wooly thread or the like, seams are more

stabilized by passing thread through looper thread auxiliary thread tension 7.

™ When threading is not properly

performed, not only sewing trouble occurs, but also needle breakage is caused. So, be careful.

Engraved marker line

Do not pass thread.

Standard Adjustment Results of lmproper Adjustment

–7 –

(2) Adjusting the rocking thread take-up

Standard Adjustment

1. Length of the rocking thread take-up

(1) It is the standard that the length of rocking thread take-up 2 from the center of the shaft of rocking thread take-up

support arm 4 to the thread hole face of rocking thread take-up 2 is 95 mm.

2. Position of the rocking thread take-up

(1) Install so that rocking thread take-up 2 is flush with rocking thread take-up 2 when the needle bar is in its lowest

position.

3. Timing of the rocking thread take-up

(1) It is the standard timing that rocking thread take-up 2 is in

its lowest position as well when the needle bar is in its lowest position. Timing of rocking thread take-up 2 is performed by adjusting the position of rocking thread take-up ball arm 8.

4. Relation between the timing of rocking thread take-up and the needle thread loop

(1) When using the excessively stretchable thread or the hard-

to-stretch thread, the size of needle thread loop can be changed by by changing the timing of rocking thread takeup 2.

(2) Relation between the timing of the rocking thread take-up

and the size of needle thread loop is as shown in the table on the next page. (The relation becomes reverse when using the needle bar thread take-up = standard seams and when it is not used = soft seams. So, be careful.)

95 mm

Flush

4mm

Anti-operator’s side

Operator’s side

–8 –

Standard Adjustment Results of lmproper Adjustment

™ When length of rocking thread take-

up 2 is lengthened, needle thread is tightened.

(Caution) When lengthening rocking

thread take-up 2, check whether it comes in contact with the thread take-up cover.

™ When length of rocking thread take-

up 2 is shortened, needle thread is loosened.

™ When installing position of rocking

thread take-up 2 is raised, needle thread is loosened when the needle bar thread take-up is used, and needle thread is tightened when the needle bar thread take-up is not used.

1. Length of the rocking thread take-up

(1) Loosen screws 1 and move rocking thread take-up 2 to the right

or left to adjust the length.

2. Position of the rocking thread take-up

(1) Loosen screw 5 and move rocking thread take-up 2 up or down

to adjust the position.

(Caution) When adjusting the position of rocking thread take-up 2,

adjust the rocking thread take-up to the same plane of the edge of rocking thread take-up shaft 3 and fix it so that spreader thread take-up 6 and spreader thread guide 7 do not come in contact with each other.

3. To adjust the timing of the rocking thread take-up 2 , remove the top cover, loosen setscrew 9 in the rocking thread take-up ball arm and move the position of rocking thread take-up ball arm 8 to and fro.

(1) Standard adjustment figure is the position where the rear end (anti-

operator’s side) of rocking thread take-up ball arm 8 aligns with engraved marker line !0 on rocking thread take-up shaft 3. (As the standard at this time, note that the clearance provided between the rear end of rocking thread take-up ball arm 8 and thrust collar !1 is 4 mm.)

(Caution) 1. When loosening screw 9 in rocking thread take-up

ball arm 8, there is a case where rocking thread take-up 2 rotates by its weight. After the adjustment, be sure to check the rocking position (flush at the lowest position) of rocking thread take-up 2.

2. When moving rocking thread take-up ball arm 8 to the operator’s side, adjust rocking thread take-up ball arm 8 within the range where it does not come in contact with rocking thread take-up bushing !2 (operator’s side).

4. Relation between timing of rocking thread take-up and needle thread loop

When needle bar thread take-up is used Loop becomes small. Loop becomes large. When needle bar thread take-up is not used Loop becomes large. Loop becomes small.

Advance timing

(Move to anti-operator’s side.)

Delay timing

(Move to operator’s side.)

Adjusting procedure is the same as step 3. Loosen setscrew 9 in rocking thread take-up ball arm 8 and adjust the position of rocking thread take-up ball arm 8.

(Caution) Adjust the timing of rocking thread take-up 2 each time in accordance with thread used or conditions.

–9 –

Standard Adjustment

1. Position of the needle thread guide rod

(1) It is the standard that the height of needle thread guide rods 1 is the position where the dimensions from the top

surface of needle thread guide base 2 to the bottom end of the hole are as follows. Left needle A : 7 mm Middle needle B : 15 mm Right needle C : 23 mm

2. Adjusting the position of needle thread guide base and silicon container thread guide

(1) It is the standard that the height of silicon containder thread guide 4 (refer to 2. CONFIGURATION OF THE

MACHINE COMPONENTS) is the position where the height from the center of setscrew 5 to the bottom end of thread hole is 9 mm.

(2) Move the lateral position of needle thread guide base 2 fully to the right of slot (43 mm).

Extreme right position

A : 7mm B : 15mm C : 23mm

Extreme right position

43mm

9mm

(3) Adjusting the position of the needle thread guide rod

–10 –

Standard Adjustment Results of lmproper Adjustment

1. Loosen setscrews 3, adjust the height of respective needle thread guide rods 1, and fix the rods with setscrews 3.

(Caution) 1. Move the lateral position of needle thread guide base 2

fully to the right of slot.

2. When adjusting the height of needle thread guide rods 1, install the rods so that the thread holes are parallel to the thread holes of silicon container thread guide 4 so that excessive resistance is not applied to threads.

2. Adjusting the position of needle thread guide base and silicon container thread guide

(1) Loosen setscrews 5 and 6 and move silicon container thread

guide 4 up or down to adjust the height.

(2) Loosen setscrew 7 and adjust the lateral position of needle thread

guide base 2.

™ When needle thread guide rod 1 is

raised, needle thread is loosened.

™ When needle thread guide rod 1 is

lowered, needle thread is tightened.

™ When silicon container thread guide

4 is raised, needle thread is loosened.

™ When silicon container thread guide

4 is lowered, needle thread is tightened.

™ When needle thread guide base 2 is

moved to the left, needle thread is loosened.

–11 –

(4) Adjusting the position of the thread receiver

Standard Adjustment

1. Position of the needle bar thread take-up thread receiver (in case of standard seams)

(1) It is the standard that the height of needle bar thread take-up thread receiver 1 is in the position where the bottom

end of thread hole to the center of needle bar thread take-up 2 aligns with the top surface of needle bar thread take-up thread receiver 1 when the needle bar is in its lowest position.

1. Position of the rocking thread take-up thread receiver (in case of soft seams) (In case thread is not passed through needle bar thread take-up 2)

(1) It is the standard that the height of rocking thread take-up receiver 7 is in the position where the top surface of

rocking thread take-up receiver 7 is in the range of the center to the top end of thread hole 9 of rocking thread take-up 8 when rocking thread take-up 8 is in its lowest position.

This range

Thread hole

Center of hole

To align

–12 –

Standard Adjustment Results of lmproper Adjustment

1. Loosen setscrew 3 and move needle bar thread take-up thread receiver 1 up or down to adjust the height.

2. When desired to make needle bar thread take-up thread receiver 1 work especially on the right needle where loop is hard to be made, adjust the height of right needle thread receiver 4 with setscrew 5.

1. Loosen setscrew !0 and move rocking thread take-up receiver 7 up or down to adjust the height.

2. When desired to make rocking thread take-up receiver 7 work especially on the right needle where loop is hard to be made, adjust the height of the right needle thread receiver 6 with screw !1.

™ When the needle bar thread take-up

thread receiver 1 is raised, loop becomes large.

™ When the needle bar thread take-up

thread receiver 1 is excessively raised,

–13 –

Standard Adjustment

(5) Adjusting the position of the spreader thread guide and spreader thread take-up

1. Relation of the position between spreader thread take-up 1 and spreader thread guide 2 is the standard when the top end of thread hole 3 of spreader thread guide 2 aligns with the bottom end of slot 5 of spreader thread take-up 1 when spreader thread take-up 1 is in its highest position. Adjust the relation of the position so that thread is moderately stretched when spreader thread take-up 1 is in its highest position in accordance with thread used or conditions.

2. Standard position of the spreader auxiliary thread tension Standard adjustment figure of the spreader auxiliary thread tension is the standard when the top end of thread tension rod 6 is flush with knob 7.

To align

Highest position

–14 –

1. Loosen setscrews 4 in spreader thread guide 2 and adjust the position of spreader thread guide 2. (Spreader thread take-up 1 is fixed to rocking thread take-up 9 and can not be adjusted in the height direction.)

2. After the adjustment, turn the sewing machine by hand and check whether spreader thread take-up 1 comes in contact with spreader thread guide 2, or section A of clearance is too small.

3. Adjusting procedure of the clearance

(1) Loosen setscrews 4 in spreader thread guide 2 and adjust in the

lateral direction, or loosen setscrews 8 in the rocking thread takeup and move spreader thread take-up 1 to the right or left to adjust the clearance.

(Caution) When loosening setscrews 8 in the rocking thread take-

up and adjusting the position of spreader thread take-up 1, adjust so that 95, length of rocking thread take-up 9 (95mm) does not change.

Standard Adjustment Results of lmproper Adjustment

™ When the relation of position between

spreader thread take-up 1 and the spreader thread guide is not proper, sewing troubles such as stitch skipping and the like will be caused.

™ If thread is less stretched and

slackness of thread occurs at the thread take-up section when spreader thread take-up 1 is in its highest position, the spreader fails to pick up thread and stitch skipping occurs.

™ If stretch or feeding of thread is

excessive when spreader thread takeup 1 is in its highest position, not only thread on the seam side is drawn and needle thread can not be tightened, but also needle bend or needle breakage will be caused.

™ If stretch or feeding of thread is

excessive when spreader thread takeup 1 is in its lowest position, thread slacks when the spreader moves from left to right and stitch skipping occurs.

–15 –

Standard Adjustment

1. Height of the spreader It is the standard that the height from the top surface of throat plate 2 to the bottom surface of spreader 1 is 8.3 to 8.7 mm.

2. Longitudinal position of the spreader It is the standard that when spreader 1 returns from the extreme left position to the right and top end A of thread hooking section reaches to the front of left needle, the clearance between the spreader and the left needle is 0.1 to 0.3 mm.

3. Protruding amount It is the standard that the dimension from the center of left needle to top end A of thread hooking section, when spreader 1 is in the extreme left position, is 4.5 to 5.5 mm.

4. Spreader stroke It is the standard that the spreader stroke is 16 to 18 mm at the stroke of thread hooking section.

5. Timing of the spreader Standard position is the position where the spreader 1 is in the extreme left position when the needle bar comes down from the upper dead point by 1.1±0.1 mm.

(6) Adjusting the spreader

8.3 to 8.7 mm

0.1 to 0.3 mm

4.5 to 5.5 mm

16.0 to 18.0 mm

Extreme left position

–16 –

Standard Adjustment Results of lmproper Adjustment

1. Adjusting the height of the spreader

2. Adjusting the longitudinal position of the spreader Loosen setscrew 3 and adjust the height and longitudinal position of the spreader 1.

3. Protruding amount of the spreader Loosen setscrew 4 in the spreader folder and adjust the protruding amount. Adjust aiming the adjustment figure of 5 mm.

4. Adjusting the spreader stroke Standard position is the position where the engraved marker line of spreader drive lever 5 aligns with the center of the shaft of connecting pin 6. When desired to increase the stroke, loosen lock nut 7 and move in the right direction. When desired to decrease the stroke, loosen lock nut 7 and move in the left direction. Adjust aiming the adjustment figure of 17 mm.

5. Adjusting the timing between the needle bar and the spreader When changing the timing, loosen two setscrews 9 in spreader eccentric cam 8 to adjust. Standard position is the position where notch !0 in the main shaft aligns with notch !1 in spreader eccentric cam. When changing, turn the upper pulley and change with spreader eccentric cam 8 fixed.

™ Height of the spreader is improper,

stitch skipping of spreader occurs.

™ Adjust the height in accordance with

the needle gauge.

™ Even when the protruding amount is

excessive or insufficient, stitch skipping of spreader will be caused.

™ When the protruding amount is

insufficient, it will be the cause for left needle not to scoop covering thread at overlapped section.

™ When the stroke is increased, disorder

of covering thread stitching will be caused.

™ When the stroke is decreased, stitch

skipping of spreader will be caused.

™ When the timing is excessively

advanced, needle does not take covering thread when it comes down and stitch skipping will be caused.

™ When the timing is excessively

retarded, resistance increases when covering thread slips out from the spreader and a load is applied to the right needle. As a result, needle breakage or stitch skipping will be caused.

(Caution) When changing, temporarily

tighten No. 2 screw in the rotation direction of setscrews 9 and turn the upper pulley to change.

–17 –

Standard Adjustment

6. Adjustment figures of the spreader thread guide

(1) It is the standard that the clearance provided between spreader 1 and spreader thread guide !2 is 0.4 to 1.0 mm. (2) It is the standard that the clearance provided between spreader thread guide !2 and needle clamp thread guide !3

is 0.8 to 1.2 mm.

(3) Lateral position of the spreader thread guide

Top end of thread hooking section D of the spreader aligns with center E of slot C in spreader thread guide !2 when spreader 1 is in the extreme right position.

(6) Adjusting the spreader

0.8 to 1.2 mm

0.4 to 1.0 mm

–18 –

Standard Adjustment Results of lmproper Adjustment

6. Spreader thread guide

(1) Adjust the height of spreader 1 to 8.3 to 8.7 mm. Loosen setscrews

!5 in the spreader thread guide and adjust the clearance provided between the top surface of spreader 1 and spreader thread guide !2 to 0.4 to 1.0 mm.

(2) Needle clamp thread guide

Loosen setscrew !4 in the needle clamp thread guide and adjust the clearance provided between the needle clamp thread guide and spreader thread guide !2 to 0.8 to 1.2 mm.

(3) For the lateral direction, align the hole of needle clamp thread guide

!3 to the prolonged line of the slot of spreader thread guide.

(Caution) When adjusting spreader thread guide !2 in the lateral

direction, check whether there is any contact at section B (left side of spreader thread guide !2 and needle clamp !6)

™ When height or position of the

spreader thread guide is improper, stitch skipping of spreader thread will be caused.

™ When height or position of the needle

clamp thread guide is improper, stitch skipping of spreader thread will be caused.

8.3 to 8.7 mm

–19 –

Standard Adjustment

(7) Adjusting the timing relation between the looper and needle bar

1. Timing relation between the looper and the needle bar (synchronization) It is the standard that dimension A from the top end of needle eyelet to the blade point of looper passes the rear of the needle and comes to the position of the right end of left needle is the same as dimension B from the top end of needle eyelet to the blade point of looper when needle bar comes down from the upper dead point, the blade point of looper passes the front of needle bar and comes to the position of the right end of left needle. (A=B)

Going of looper

Returning of looper

–20 –

Standard Adjustment

Results of lmproper Adjustment

1. To adjust the timing relation between the needle and the looper, remove the top cover, loosen four setscrews 1 in the sprocket and turn upper pulley 2 in the state that the sprocket is held.

2. Adjusting procedure

(1) When adjusting the timing to "0" (zero)

1) In case dimension A when the looper advances is smaller than dimension B when the looper retreats, the looper timing is retarded (needle timing is advanced). In this case, loosen setscrews 1 in the sprocket and finely turn upper pulley 2 in the reverse direction.

2) In case dimension A when the looper advances is larger than dimension B when the looper retreats, the looper timing is advanced (needle timing is retarded). In this case, loosen setscrews 1 in the sprocket and finely turn upper pulley 2 in the normal direction.

(Caution) Be careful not to excessively turn upper pulley 2.

3. After the adjustment, fix four setscrews 1 in the sprocket.

™ When the difference in timing (going

and returning) of looper is excessively large, stitch skipping or entangling of needle thread will be caused.

+ 52 hidden pages

JUKI MF-7700 Series Engineer's Manual

Specifications and Main Features

Frequently Asked Questions

User Manual